The Dot was designed by Akio Yamamoto, who was also behind the designs of a dozen or more other Cast Puzzles and the multi-coloured series of Naked Secret Boxes.
The object is to take apart the puzzle into two separate pieces. Initial impression was that the Dot is similar to the Cast Diamond, designed by Scott Elliot. In some ways it is, but the solve in my opinion is harder than the Diamond. It took me a bit of fiddling before I managed to split the two pieces. I tried to remember the moves for later re-assembly but the latter was a tad more difficult than I expected.
DOT, according to one Hanayama insider familiar with the puzzle stands for (D)-Direction:(O)-Orientation:(T)-Twist...very appropriate since you need to employ all three to solve the DOT.
While the Diamond requires a "one-move" sort of motion" to "fuse" the two separate parts together once you have found the rather precise point of entry, the Dot requires a few more steps. The way the design has been carried out seems like you have to link the parts initially through a sort of mini maze with several twists and turns until you hit a certain "sweet spot"; and wah-la , the two parts suddenly come together and fit (just) so precisely and nicely. Get the orientation wrong at the start and you will remain stuck. Again, because you can see everything that you are doing, so long as you persevere, you will eventually solve it at some point.
Repeat solving becomes progressively easier as you memorise the moves but my second and third attempts at re-solving took me almost as long as my first time, even though I knew how the pieces were suppose to interact with each other.
The parts of the Dot are very precisely cut and does look a bit delicate. While it is robustly made and can probably stand up to some rough handling, the Dot does not require any force whatsoever and you may damage the puzzle if you force any move by overly twisting or turning. This particular Cast puzzle does require a bit more delicate handling during play than some of the other Cast puzzles in the series.